The present invention relates generally to equipment utilized and methods performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a single line control module for well tool actuation.
A variety of well tools are available which may be operated or actuated by application of pressure. For example, a production valve or choke may be opened or closed by applying pressure to a control line extending to a remote location, such as the earth's surface or another location in the well. Many other types of well tools and pressure application methods are available, as well.
In instances where a well tool is operated by control line pressure, it is known to use a separate control line for each mode of operation. For example, a downhole valve may be opened by increasing pressure on one control line, and the valve may be closed by increasing pressure on another control line. However, the use of multiple control lines increases the cost and time required to complete an installation and in some applications, such as subsea wells, the number of control lines or umbilicals is severely limited.
For these reasons, there is a need to reduce the number of control lines used to operate well tools. Some systems have been proposed in the past which use a single control line to operate a downhole well tool. However, for the most part these systems have been unduly complex and, thus, unreliable and expensive.
Therefore, it may be seen that a need exists for improvements in operating downhole well tools using a single control line.